JP7463808B2 - Valve mechanism - Google Patents

Description

The present invention relates to a valve device, and in particular to a ball valve.

Conventionally, valve devices are installed in pipes through which fluids such as city gas flow in order to block or open the flow of the fluid. Ball valves with a spherical valve body are widely used as valve devices, and ball valves made of synthetic resin (e.g., polyethylene resin) that is highly flexible and resistant to corrosion are widely used.

Generally, a ball valve comprises a substantially cylindrical valve box with an opening that communicates with the flow path, a spherical valve body that is rotatably mounted within the valve box, and a ring-shaped seat member that seals between the valve body and the valve box (see, for example, Patent Document 1). With this configuration, the valve body can be operated from outside the ball valve to open and close the flow path, thereby blocking or opening the flow of fluid in the piping. A rubber member such as nitrile butadiene rubber is used for the seat member, and the flow path is blocked by pressing the valve body against this seat member.

JP 2019-49333 A

From the viewpoint of ease of opening and closing the valve disc, it is desirable that the torque required for operating the valve disc be large enough to allow easy opening and closing. It is also desirable that low torque be maintained for a long period of time even when the valve disc is repeatedly opened and closed. In conventional ball valves, lubricating grease is applied to the seat member to reduce the torque required for operating the valve disc.

However, for example, when a ball valve is used in an environment where foreign matter such as sand or dust is present in the fluid, the configuration using the lubricating grease described above may cause the foreign matter to adhere to the lubricating grease when it comes into contact with it. As a result, the foreign matter may become caught in the valve seat and increase the friction between the seat member and the valve body, which may increase the operating torque of the valve body. In addition, the trapped foreign matter may cause the seal between the seat member and the valve body to become insufficient, making it impossible to reliably shut off the fluid. Furthermore, in cases where the flow path is not opened or closed frequently, the valve body and seat member may become stuck together via the lubricating grease, which may increase the operating torque.

The present invention was made in consideration of the above circumstances, and aims to provide a valve device that can reduce operating torque for a long period of time and prevent foreign matter from becoming caught.

The valve device of the present invention is a valve device that blocks or opens a flow path in a pipe, and the valve device includes a substantially cylindrical valve box having an opening communicating with the flow path, a ring-shaped sheet member attached around the opening in the valve box, and a valve body that is rotatably provided in the valve box and blocks the flow path by being pressed against the sheet member. The sheet member has a rubber base material, a first fluororesin layer formed on the surface thereof directly or via a base layer, the first fluororesin layer containing particles of a first fluororesin and a resin binder, and a second fluororesin layer formed on the first fluororesin layer containing particles of a second fluororesin.

In the present invention, it is preferable that the valve device does not have grease between the seat member and the valve body.

Furthermore, in the present invention, in the first fluororesin layer, the particles of the first fluororesin are preferably polytetrafluoroethylene resin particles, and the resin binder is preferably a urethane resin binder.

Furthermore, in the present invention, it is preferable that the second fluororesin particles are polytetrafluoroethylene resin particles, and the second fluororesin layer is a layer in which the polytetrafluoroethylene resin particles are deposited.

In the present invention, the valve body and the valve body may be made of synthetic resin, and the valve device may be a ball valve that blocks or opens the gas flowing through the flow path in the piping.

The valve device of the present invention has such a configuration that foreign matter is less likely to adhere to the seat member, making it possible to reduce the operating torque of the valve body for a long period of time and prevent foreign matter from becoming caught.

1 is an explanatory diagram showing a schematic configuration of an entire valve device according to the present invention; FIG. 4 is a schematic cross-sectional view showing a valve body in a fully open state. FIG. 4 is a schematic cross-sectional view showing a valve body in a fully closed state. 2A to 2C are diagrams for explaining a layer structure of a sheet member. FIG. 4 is a diagram showing the relationship between the number of times the valve disc is opened and closed and the operating torque. FIG. 11 is a diagram showing the relationship between the idle time and the initial operation torque. FIG. 13 is a partial enlarged view of a seat member in a conventional valve device.

Figure 1 is an explanatory diagram showing the overall schematic configuration of a valve device according to the present invention. In Figure 1, a ball valve is shown as the valve device. The ball valve 1 is a device that is placed in the middle of a flow path in a pipe through which a fluid or the like flows, and blocks or opens the flow path. As shown in Figure 1, the ball valve 1 comprises a substantially cylindrical valve box 3, a valve element 2 that is rotatably provided in the valve box 3, and a ring-shaped seat member 4 that is attached to the valve box 3. In Figure 1, the fluid flows in the direction of the arrow. Pipes (not shown) are connected to the upstream and downstream sides of the valve box 3. Note that Figure 1 shows a fully open state in which the valve element 2 opens the flow path.

As shown in FIG. 1, the valve box 3 is integrated by fitting the body 31 and the side 32. The valve body accommodating section 33 in which the valve body 2 is accommodated is formed in the center of the integrated valve box 3. The valve box 3 has openings 34a, 34b on both sides of the valve body accommodating section 33, which communicate with the upstream flow path 37a and the downstream flow path 37b. Around the openings 34a, 34b, stepped sections 35a, 35b are formed that protrude radially inward so that the inner circumferential surface of the valve box 3 is reduced in diameter, and the seat members 4, 4 are attached to the stepped sections 35a, 35b, respectively. In addition, in the valve box 3, an attachment hole 36 that penetrates the inner circumferential surface and the outer circumferential surface is formed in the direction along the rotation axis of the valve body 2, and the valve rod 5 is rotatably inserted into the attachment hole 36.

The valve disc 2 is connected to the end of the valve rod 5 in the valve body housing portion 33 in the valve box, and the valve disc 2 rotates as the valve rod 5 rotates. The rotation axis of the valve rod 5 and the rotation axis of the valve disc 2 are the same. The valve disc 2 has a spherical outer surface 21 and a through hole 22 that penetrates the inside. In the valve disc 2, a recess 23 is formed on one side in the direction along the rotation axis of the valve disc 2, and a pin mounting hole 24 that penetrates the through hole 22 and the outer surface 21 is formed on the other side. The end of the valve rod 5 is fixed to the recess 23, and a pin 6 is inserted into the pin mounting hole 24 so as to straddle the pin groove of the valve box 3.

In FIG. 1, ball valve 1 is a ball valve made of synthetic resin, and valve body 2 and valve box 3 are each made of a resin material. Examples of resin materials that can be used include polyethylene resin.

The operation of the valve body 2 will be explained using Figures 2 and 3. Figures 2 and 3 are partial cross-sectional views of the valve body of Figure 1, viewed from the valve rod side. Figure 2 shows the fully open state of the valve body 2, with the through hole 22 of the valve body 2 parallel to the flow path. When the valve body 2 rotates 90 degrees around the rotation axis from the fully open state of Figure 2, it reaches the fully closed state of Figure 3. In Figure 3, the through hole 22 of the valve body 2 is perpendicular to the flow path, and the flow path is blocked by the valve body 2 coming into close contact with the seat member 4. When the flow path is blocked, the seat member 4 is pressed against the valve body 2 and elastically deforms.

Here, the configuration of a conventional ball valve is shown in FIG. 7. FIG. 7 is an enlarged view of the portion corresponding to part A in FIG. 1, showing the valve body in a fully open state. In the ball valve 11, a semi-solid lubricating grease 15 (hereinafter, sometimes simply referred to as grease 15) is applied to the seal surface 14a of the seat member 14 that contacts the valve body 12. By interposing the grease 15 between the valve body 12 and the seat member 14, the operating torque of the valve body 12 is reduced and the rotation of the valve body 12 is made smooth. However, it is assumed that foreign matter such as sand, dust, metal powder, and dirt may be mixed into the fluid due to a trouble. In such a case, in the conventional configuration, when the foreign matter comes into contact with the grease 15, the foreign matter may adhere to the grease 15 due to the adhesive action of the grease 15. If the valve body 12 is opened and closed with the foreign matter attached, the foreign matter may be caught between the valve body 12 and the seat member 14, which may wear the seat member and the like, leading to an increase in the operating torque of the valve body.

In contrast, the valve device of the present invention has a resin coating on the seat member with two fluororesin layers on the surface, making it highly durable and reducing the operating torque for a long period of time while preventing foreign matter from getting caught. In particular, the fluororesin layer (second fluororesin layer) on the outermost layer side of the seat member that comes into contact with the valve body is formed from a quick-drying lubricant (dry grease), making it possible to prevent the adhesion of foreign matter.

The configuration of the seat member according to the present invention will be described with reference to FIG. 4. FIG. 4(a) shows a plan view of the seat member from the sealing surface side, and FIG. 4(b) shows a cross-sectional view of the sealing surface. As shown in FIG. 4(a), the seat member 4 is ring-shaped, and a tapered portion that expands in diameter toward the outer diameter side is formed around the entire circumference at the inner diameter side end. This tapered portion becomes the sealing surface with the valve body 2 (see FIG. 1). In the embodiment shown in FIG. 4(a), the resin coating L is formed only on this tapered portion. Note that the resin coating L only needs to be formed on at least the sealing surface that contacts the valve body. For example, it may be formed on the entire surface of the seat member 4, or it may be formed on the end face (including the tapered portion) on one axial side of the seat member 4.

The specific configuration of the resin coating L is described in FIG. 4(b). As shown in FIG. 4(b), the resin coating L has a first fluororesin layer 42 formed directly on the surface of the rubber substrate 41, and a second fluororesin layer 43 formed on the surface of the first fluororesin layer 42. The rubber material of the rubber substrate 41 is not particularly limited, and examples thereof include natural rubber, nitrile butadiene rubber (NBR), styrene rubber, butadiene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, chloroprene rubber, fluororubber, urethane rubber, and silicone rubber. Among these, for example, in a valve device for city gas, it is preferable to use NBR, which has low gas permeability and small compression set.

In the configuration of FIG. 4(b), the first fluororesin layer 42 is formed directly on the surface of the rubber substrate 41, but the first fluororesin layer 42 may be formed via a primer layer (undercoat layer). For example, a polyolefin resin paint may be applied to the surface of the rubber substrate 41 to form a polyolefin resin layer as an undercoat layer. This can improve the adhesion between the resin coating L and the rubber substrate 41. A roughening treatment may also be applied to roughen the surface of the rubber substrate 41. For the roughening treatment, a mechanical roughening method such as a shot blasting method or a chemical roughening method such as an alkali treatment may be used.

The first fluororesin layer 42 is a layer containing particles of the first fluororesin and a resin binder. As shown in FIG. 4(b), the fluororesin particles 421 are dispersed in the resin binder 422. Any resin binder capable of dispersing the fluororesin particles can be used as the resin binder. Examples of resins that can be used include urethane resin, acrylic resin, polyamide-imide resin, and polyimide resin. In particular, it is preferable to use a urethane resin binder that is highly flexible and elastic.

A urethane resin is a polymer having a urethane bond in its composition, and can be obtained, for example, by reacting a compound containing an isocyanate group with a compound containing a hydroxyl group. Examples of compounds containing an isocyanate group include polyisocyanate components such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and xylylene diisocyanate (XDI). Examples of compounds containing a hydroxyl group include polyol components such as polyester polyol, polyether polyol, acrylic polyol, copolymer of hydroxyl group-containing fluoroolefin and alkyl vinyl ether (FEVE), and polytetramethylene ether glycol (PTMG).

The fluororesin particles 421 contained in the first fluororesin layer 42 may be polytetrafluoroethylene (PTFE) resin particles, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA) particles, tetrafluoroethylene-hexafluoropropylene copolymer (FEP) particles, ethylene-tetrafluoroethylene copolymer (ETFE) particles, polyvinylidene fluoride (PVDF) particles, or the like. These resin particles may be used alone or as a mixture of two or more kinds. Among the above fluororesin particles, PTFE resin particles are preferred because of their excellent frictional properties and heat resistance.

The average particle diameter of the fluororesin particles 421 contained in the first fluororesin layer 42 is preferably 15 μm or less. By making it 15 μm or less, dispersibility can be improved. The average particle diameter of the fluororesin particles is the particle diameter of 50% by mass measured by a laser diffraction scattering type particle size distribution measurement method. The average particle diameter of the fluororesin particles 421 is preferably 10 μm or less. The content of the fluororesin particles 421 in the entire first fluororesin layer 42 is, for example, 10% by mass to 60% by mass, and preferably 10% by mass to 40% by mass.

To form the first fluororesin layer 42, a resin paint in which fluororesin particles are dispersed is used. For example, when a urethane resin binder is used as the resin binder, the resin paint may be prepared by mixing a predetermined amount of the urethane resin binder and fluororesin particles in a solvent, or a commercially available product may be used. An example of a commercially available resin paint is FD-2760 manufactured by Toyo Drylube Co., Ltd. The fluororesin particles are uniformly dispersed by kneading the resin paint with a kneading device such as a triple roll, ball mill, attritor, or bead mill. After dispersion, the resin paint is applied to the rubber substrate 41 by a method such as spraying, brushing, or dipping, and then cured at a predetermined curing temperature to form the first fluororesin layer 42. The curing temperature is, for example, 80°C to 150°C.

The thickness of the first fluororesin layer 42 is preferably 5 μm to 30 μm. By keeping the thickness within this range, peeling due to poor adhesion of the first fluororesin layer and the occurrence of cracks during layer formation can be suppressed. In addition, the thickness is preferably 5 μm to 15 μm.

Next, the second fluororesin layer will be described. In FIG. 4(b), the second fluororesin layer 43 is a layer containing fluororesin particles 431. Specifically, the second fluororesin layer 43 is a layer in which the binder component is low or substantially absent, and the fluororesin particles 431 are deposited. The binder component content is, for example, 10% by mass or less, and preferably 5% by mass or less, relative to the entire second fluororesin layer 43. In the valve device according to the present invention, the oil-free dry layer 43 is in direct contact with the outer surface of the valve body without the interposition of lubricating grease, and therefore, compared to the conventional configuration (see FIG. 7), adhesion of foreign matter can be prevented. In addition, the second fluororesin layer 43 is a dense layer containing fluororesin particles 431. The second fluororesin layer 43 has excellent durability due to the strong chemical bonding force of fluorine atoms. Furthermore, since the friction coefficient of fluororesin is small, low friction can be maintained for a long period of time.

The fluororesin particles 431 of the second fluororesin layer 43 can be PTFE resin particles, PFA resin particles, FEP resin particles, ETFE resin particles, PVDF resin particles, etc. The fluororesin particles 431 and the fluororesin particles 421 of the first fluororesin layer 42 may be resin particles made of the same resin, or may be resin particles made of different resins. The average particle diameter of the fluororesin particles 431 is preferably 10 μm or less, and more preferably 5 μm or less. The average particle diameter of the fluororesin particles 431 is preferably smaller than the average particle diameter of the fluororesin particles 421 of the first fluororesin layer 42.

The second fluororesin layer 43 is formed by applying a volatile paint in which fluororesin particles are dispersed in an organic solvent or water, and then drying. There are no particular limitations on the organic solvent, so long as it is quick-drying and capable of dispersing fluororesin particles, but for ease of film formation, it is preferable for the boiling point to be 100°C or less, and more preferably 80°C or less. Among organic solvents, it is preferable to use hydrofluoroether, which has excellent quick-drying properties and is environmentally friendly.

The hydrofluoroether is represented by the following general formula (1).
C _n F _2n+1 -O-C _x H _2x+1 ... (1)
In the formula (1), n and X are each an integer of 1 or more.

Examples of hydrofluoroethers include methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, methyl nonafluoroisobutyl ether, ethyl nonafluoroisobutyl ether, and 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane. As the hydrofluoroether, these compounds may be used alone or in combination of two or more.

The volatile paint in which the fluororesin particles are dispersed may be prepared by mixing a predetermined amount of the fluororesin particles with an organic solvent or water, or a commercially available product may be used. An example of a commercially available product using hydrofluoroether as the organic solvent is LBF-731 manufactured by Toyo Drylube Co., Ltd. In the volatile paint, the fluororesin particles are preferably contained in an amount of 1% by mass to 10% by mass based on the total amount of the volatile paint. The volatile paint is kneaded with a kneading device to uniformly disperse the fluororesin particles. After dispersion, the volatile paint is applied onto the first fluororesin layer 42 by a method such as spraying, brushing, or dipping, and then dried at a predetermined temperature to form the second fluororesin layer 43. The drying temperature is, for example, 20°C to 80°C.

In addition, various additives can be added to the above-mentioned volatile paints. For example, surfactants, dispersants, rust inhibitors, anticorrosive agents, antioxidants, extreme pressure agents, adhesion improvers, oiliness agents, etc. can be added.

In a particularly preferred embodiment of the resin coating L, the resin coating L has a first fluororesin layer 42 in which the fluororesin particles 421 are PTFE resin particles, the resin binder 422 is a urethane resin binder, and the resin layer has a thickness of 5 μm to 20 μm, and a second fluororesin layer 43 in which PTFE resin particles are deposited as the fluororesin particles 431. Furthermore, it is preferable that the thickness of the second fluororesin layer 43 is smaller than the thickness of the first fluororesin layer 42.

In the above Figures 1 to 4, a synthetic resin ball valve is described, but the valve body and valve box may be made of a metal material such as stainless steel. Furthermore, the valve device of the present invention is not limited to ball valves, and can be applied to valve devices other than ball valves.

To confirm the performance of the valve device of the present invention, durability tests, sticking resistance tests, and foreign matter resistance tests were conducted using each sheet member with modified specifications.

Example 1
As a pretreatment, OR Primer (trade name, manufactured by Origin Chemical Construction Co., Ltd.) was applied to the sealing surface of a ring-shaped NBR substrate (outer diameter: 175 mm, inner diameter: 139 mm) and dried at 100°C for 20 to 30 minutes. Then, a resin paint (manufactured by Toyo Drylube Co., Ltd., FD-2760) in which PTFE resin particles are dispersed in a urethane resin binder was applied by spraying on the primer layer, and baked at 100°C for 60 minutes to harden the resin binder, thereby forming a first fluororesin layer. Furthermore, a volatile paint (manufactured by Toyo Drylube Co., Ltd., LBF-731) in which PTFE resin particles are dispersed in hydrofluoroether was applied by brush painting on the resin layer, and dried at 23°C for 10 minutes to form a second fluororesin layer. The obtained sheet member was attached to the ball valve shown in FIG. 1 to obtain a test valve.

Comparative Example 1
Silicone grease (HIVAC-G, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied as a semi-solid lubricating grease to the sealing surface of a ring-shaped NBR substrate (outer diameter: 175 mm, inner diameter: 139 mm), and the seat member was then attached to the ball valve shown in Figure 1 to obtain a test valve.

Reference Example 1
As in Example 1, a seal surface of a ring-shaped NBR substrate (outer diameter: 175 mm, inner diameter: 139 mm) was coated with OR Primer (trade name, manufactured by Origin Kaken Kogyo Co., Ltd.) as a pretreatment and dried at 100°C for 20 to 30 minutes. Then, on the primer layer, a resin paint (FD-2760, manufactured by Toyo Drylube Co., Ltd.) in which PTFE resin particles are dispersed in a urethane resin binder was sprayed and baked at 100°C for 60 minutes to harden the resin binder, forming a first fluororesin layer. The obtained sheet member was attached to the ball valve shown in FIG. 1 to obtain a test valve.

Reference Example 2
A resin coating (NTB7104, manufactured by Okitsumo Co., Ltd.) in which silicone oil was dispersed in a urethane resin binder was sprayed onto the sealing surface of a ring-shaped NBR substrate (outer diameter: 175 mm, inner diameter: 139 mm), and the resin binder was cured by baking at 150° C. for 60 minutes to form a silicone oil layer. The obtained sheet member was attached to the ball valve shown in FIG. 1 to obtain a test valve.

(1) Durability Test In this test, test valves of the Example, Comparative Example, and Reference Example 1 were used. For each test valve, the operation torque was measured when the valve body was repeatedly opened and closed. Opening and closing operations were repeated at intervals of about 10 seconds, and a total of 500 sets of opening and closing operations were performed. The target upper limit of the operation torque was set to 150 N·m. Note that the test for Reference Example 1 was interrupted midway because it exceeded the target upper limit. Figure 5 shows the change in operation torque over time.

As shown in Figure 5, the working example was significantly below the target upper limit, and maintained a low torque up to 500 opening and closing operations. The comparative example was stable at a nearly constant operating torque, except for the first opening and closing operation. In contrast, in Reference Example 1, in which only the first fluororesin layer was formed, the operating torque increased as the number of opening and closing operations increased, and exceeded the target upper limit when the number of opening and closing operations exceeded 100. This is thought to be because the first fluororesin layer peeled off due to repeated opening and closing operations.

(2) Anti-sticking test In this test, test valves of Comparative Example, Reference Example 1, and Reference Example 2 were used. For each test valve, the valve body was left in a closed state for an arbitrary period of time (1 day to 125 days), and then the initial operating torque when opening the valve body was measured. The target upper limit of the operating torque was set to 150 N·m. Figure 6 shows the change in operating torque over time.

As shown in Figure 6, the test valve of the comparative example showed a significant increase in operating torque after one day of leaving it alone compared to the operating torque at the start of the test (day 0), and exceeded the target upper limit after several days of leaving it alone. In the test valve of the comparative example, grease was placed between the seat member and the valve body, and it is believed that the operating torque increased because the valve body was fixed by this grease. In contrast, Reference Examples 1 and 2 were below the target upper limit even after being left alone for a long period of time exceeding 40 days. Furthermore, there was almost no change in the operating torque compared to the start of the test (day 0), and no fixation was observed. Furthermore, Reference Example 1, which contains PTFE resin particles as a lubricant for the resin layer, showed a lower torque than Reference Example 2, which contains silicone oil.

Although the anti-sticking test was not performed on the test valve of the example, since the outermost surface of the example is made of a layer of PTFE resin particles and no grease is interposed between the seat member and the valve body, it is expected to show results similar to those of Reference Example 1.

(3) Foreign body resistance test In this test, the test valves of the embodiment, comparative example, and reference example 1 were used. The flow path of each test valve was arranged so as to face vertically, and about 20 g of sand was put into the flow path from above with the valve body closed. After that, the valve body was opened and closed 10 times to drop the sand from the flow path on the opposite side. 10 sets of this operation were performed, with 10 openings and closings of the valve body from the time of putting in the sand. The operation torque A when opening and closing the valve body before putting in the sand and the operation torque B when opening and closing the valve body after the completion of the 10 sets were measured, and the case where the operation torque B was 250% or less with respect to the operation torque A was marked as "○", and the case where it exceeded 250% was marked as "×". The evaluation results are shown in Table 1.

Table 1 also shows the results of the other tests mentioned above, with an "X" indicated if the operating torque exceeded the target upper limit in each test. Note that the operating torque item in Table 1 evaluates the operating torque of the initial opening and closing operation in the durability test.

As shown in Table 1, the Comparative Example had a large amount of sand attached when visually observed, and the foreign matter resistance was rated as "X", whereas the Example and Reference Example 1 had almost no sand attached, and the foreign matter resistance was rated as "O". In addition, the sealing property was also confirmed using the test valve of the Example after sand had been passed through it. Specifically, when a pressure of 0.6 MPa was applied to the flow path with the valve body of the test valve closed, no gas leakage was confirmed through the seat member.

As shown in Table 1, the ball valve of the embodiment has a fluororesin layer formed on the sealing surface between the seat member and the valve body, and no semi-solid lubricating grease is interposed between the seat member and the valve body, improving the adhesion resistance and foreign matter resistance that are disadvantageous in conventional configurations. In addition, by using a quick-drying lubricant to form a dense layer of fluororesin particles (second fluororesin layer) on top of the first fluororesin layer, it is possible to maintain operating torque and durability that are comparable to conventional configurations.

As described above, the valve device of the present invention has a seat member with two fluororesin layers, which reduces the operating torque for a long period of time and prevents foreign matter from adhering to the seat member. Therefore, even in an environment where foreign matter may be mixed into the fluid, it is possible to prevent foreign matter from getting caught, and ultimately to prevent gas leaks for a long period of time. For example, city gas can be used as the fluid.

1: Ball valve (valve device)
2: Valve body 21: Outer surface 22: Through hole 23: Recess 24: Pin mounting hole 3: Valve box 31: Body 32: Side 33: Valve body accommodating section 34a: Opening 34b: Opening 35a: Step 35b: Step 36: Mounting hole 37a: Flow path 37b: Flow path 4: Sheet member 41: Rubber substrate 42: First fluororesin layer 421: Fluororesin particles 422: Resin binder 43: Second fluororesin layer 431: Fluororesin particles 5: Valve stem 6: Pin L: Resin coating

Claims (5)

A valve device that blocks or opens a flow path in a pipe,
The valve device includes a substantially cylindrical valve box having an opening communicating with the flow path, a ring-shaped seat member attached around the opening in the valve box, and a valve body rotatably provided in the valve box and blocked off the flow path by being pressed against the seat member,
The sheet member comprises a rubber base material, a first resin layer formed on a surface of the rubber base material and containing particles of a first fluororesin and a resin binder, and a second resin layer formed on the first resin layer and containing particles of a second fluororesin. The valve device according to claim 1, characterized in that no grease is interposed between the seat member and the valve body. The valve device according to claim 1 or 2, characterized in that in the first resin layer, the first fluororesin particles are polytetrafluoroethylene resin particles, and the resin binder is a urethane resin binder. The valve device according to any one of claims 1 to 3, characterized in that the second fluororesin particles are polytetrafluoroethylene resin particles, and the second resin layer is a layer in which the polytetrafluoroethylene resin particles are deposited. The valve device according to any one of claims 1 to 4, characterized in that the valve body and the valve element are made of synthetic resin, and the valve device is a ball valve that blocks or opens the gas flowing through the flow path in the piping.

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